Laser Interferometers, Gravitational Waves and Echos from the Universe.

Laura Cadonati, University of Massachusetts, Amherst
On Behalf of the LIGO Scientific Collaboration and the Virgo Collaboration

The Laser Interferometer Gravitational-wave Observatory (LIGO) and its sister
project Virgo have the ambitious goal of the first direct detection of 
gravitational waves. Such detection will provide not only a test of General 
Relativity, but also a fundamental, new probe into the universe.
To achieve this goal, LIGO and Virgo use laser interferometers to monitor 
changes in the relative separation of mirrors at the ends of each of two 
perpendicular arms of km-scale length, in response to the space-time 
distortions induced by the passage of gravitational waves. 
This talk will give an overview of the status and the science of LIGO, with  
selected results from its initial phase and predictions for the enhanced and
advanced detector configurations.